ORIENTATION OF BARK BEETLES PITYOGENES CHALCOGRAPHUS AND IPS-TYPOGRAPHUS TO PHEROMONE-BAITED PUDDLE TRAPS PLACED IN GRIDS - A NEW TRAP FOR CONTROL OF SCOLYTIDS

A puddle trap was designed that is simple to build and efficient in ca tching bark beetles (Coleoptera: Scolytidae). The trap is insensitive to wind and should be much easier to manufacture than the more complic ated perforated pipe and barrier traps commercially available. A 7 x 7 grid of 49 puddle traps baited with aggregation pheromone components of Pityogenes chalcographus (chalcogran and methyl decadienoate) was p laced at either 1.5-, 3-, 6-, or 12-m spacing between traps in the fie ld for two or more replicates of one day length (June 1989, Torsby, Sw eden). The resulting catches showed that beetles were trapped as they flew into the grid since the inner square-ring of 24 traps caught less beetles per trap than the outer square-ring trap average (36 traps) i n most experiments. Ips typographus also landed in puddle traps primar ily on the periphery of the grid (6-m spacing only) when traps were ba ited with its pheromone components, (S)-cis-verbenol and methyl buteno l. Computer simulation of flying bark beetles in grids of traps of var ious spacings and catch radii estimated that the experimental pheromon e traps had an effective catch radius of 1.3 m or less for P. chalcogr aphus, depending on the spacing between traps. An effective catch radi us of 2 m for I. typographus was found for the 6-m grid spacing. P. ch alcographus beetles were increasingly disrupted in their orientation t o pheromone at the closer trap spacings since the effective catch radi us declined linearly with closer trap spacing. However, landing was st ill precise since unbaited puddle traps within the grid did not catch any bark beetles.